Nordenskiöld brought further evidence for this view. He was the first to decipher
parts of Scheele’s laboratory notes, and by comparing the contents of these notes
with the contents of dated letters, he concluded that Scheele had discovered oxygen
before 1773 [6]. While the latest possible date for Scheele’s discovery was set to
November 16, 1772, Nordenskiöld did not attempt to establish the first possible
date for Scheele’s discovery, as his goal was to establish Scheele’s priority over
Priestley. Although Nordenskiöld’s method of dating documents has been questioned, the conclusions were accepted by Boklund, the foremost expert on Scheele,
and most others [7].
Oseen argued that Scheele’s discovery of oxygen occurred before he came to
Uppsala [8]. In 1784, Wilcke wrote to Scheele that he suspected that Bergman
might have mentioned Scheele’s discovery of oxygen in a letter to Priestley, and
that Priestley thus had stolen Scheele’s results.
1 Two letters from Priestley to
Bergman are known, the last of which was dated October 21, 1772. That letter was,
on Priestley’s request, forwarded to Wilcke, so Wilcke was aware of the correspondence. There was no further correspondence between Priestley and Bergman.
Oseen’s interpretation of this is that Wilcke must have assumed that Bergman was
aware of Scheele’s discovery of oxygen in the summer of 1772, and that the reason
for Wilcke to believe so was that Wilcke himself had learned of Scheele’s discovery
by that time and that he assumed that Scheele’s other friends had the same
knowledge [9]. Oseen found further support in a statement by Sjöstén that “apart
from Wilcke several others had been fully informed about [the contents of Scheele’s
book] long before it saw the light of day” [10]. Since Retzius wrote to Wilcke after
Scheele’s death that he undertook the main part of his and Scheele’s joint study of
tartaric acid while Scheele focused on the experiments that formed the basis of his
book on air and fire (Sect. 21.3), Oseen concluded that Scheele had discovered
oxygen before he left Stockholm [11]. On one hand, the fact that Scheele experimented with air and fire in Stockholm does not necessarily mean that he had
discovered oxygen. On the other hand, oxygen plays such an important role in
Scheele’s book that it is hard to imagine that the isolation of oxygen constituted the
last stage of the study.
Boklund, finally, believed that Scheele may have isolated oxygen already in
Malmö around 1767–1768 [7]. A. E. Nordenskiöld’s father had met Gahn, who said
that Scheele’s first encounter with oxygen was when he observed how embers from
the fire place burned with a brilliant flash when they drifted above crucibles with hot
pyrolusite (MnO 2 ) [12]. This was due to oxygen evolved from pyrolusite on heating,
and similar effects had been noted by Merret
2 in 1668, and by Pott in 1740, but had
not been explained. Boklund argued that it is more likely that the observation was
made using fused potassium nitrate (saltpetre) than MnO 2 [7]. When the flashing
coal particles are mentioned by Scheele, it was in combination with molten potassium nitrate, not pyrolusite [13]. Scheele had investigated the formation of potassium nitrite (KNO 2 ) by heating potassium nitrate (KNO 3 ) in Malmö in 1767–1768,
1
Wilcke’s suspicion was of course unfounded.
2
Christopher Merret (c. 1615–1695). British physician and scientist.
21.1 Scheele’s Discovery of Oxygen
279
parts of Scheele’s laboratory notes, and by comparing the contents of these notes
with the contents of dated letters, he concluded that Scheele had discovered oxygen
before 1773 [6]. While the latest possible date for Scheele’s discovery was set to
November 16, 1772, Nordenskiöld did not attempt to establish the first possible
date for Scheele’s discovery, as his goal was to establish Scheele’s priority over
Priestley. Although Nordenskiöld’s method of dating documents has been questioned, the conclusions were accepted by Boklund, the foremost expert on Scheele,
and most others [7].
Oseen argued that Scheele’s discovery of oxygen occurred before he came to
Uppsala [8]. In 1784, Wilcke wrote to Scheele that he suspected that Bergman
might have mentioned Scheele’s discovery of oxygen in a letter to Priestley, and
that Priestley thus had stolen Scheele’s results.
1 Two letters from Priestley to
Bergman are known, the last of which was dated October 21, 1772. That letter was,
on Priestley’s request, forwarded to Wilcke, so Wilcke was aware of the correspondence. There was no further correspondence between Priestley and Bergman.
Oseen’s interpretation of this is that Wilcke must have assumed that Bergman was
aware of Scheele’s discovery of oxygen in the summer of 1772, and that the reason
for Wilcke to believe so was that Wilcke himself had learned of Scheele’s discovery
by that time and that he assumed that Scheele’s other friends had the same
knowledge [9]. Oseen found further support in a statement by Sjöstén that “apart
from Wilcke several others had been fully informed about [the contents of Scheele’s
book] long before it saw the light of day” [10]. Since Retzius wrote to Wilcke after
Scheele’s death that he undertook the main part of his and Scheele’s joint study of
tartaric acid while Scheele focused on the experiments that formed the basis of his
book on air and fire (Sect. 21.3), Oseen concluded that Scheele had discovered
oxygen before he left Stockholm [11]. On one hand, the fact that Scheele experimented with air and fire in Stockholm does not necessarily mean that he had
discovered oxygen. On the other hand, oxygen plays such an important role in
Scheele’s book that it is hard to imagine that the isolation of oxygen constituted the
last stage of the study.
Boklund, finally, believed that Scheele may have isolated oxygen already in
Malmö around 1767–1768 [7]. A. E. Nordenskiöld’s father had met Gahn, who said
that Scheele’s first encounter with oxygen was when he observed how embers from
the fire place burned with a brilliant flash when they drifted above crucibles with hot
pyrolusite (MnO 2 ) [12]. This was due to oxygen evolved from pyrolusite on heating,
and similar effects had been noted by Merret
2 in 1668, and by Pott in 1740, but had
not been explained. Boklund argued that it is more likely that the observation was
made using fused potassium nitrate (saltpetre) than MnO 2 [7]. When the flashing
coal particles are mentioned by Scheele, it was in combination with molten potassium nitrate, not pyrolusite [13]. Scheele had investigated the formation of potassium nitrite (KNO 2 ) by heating potassium nitrate (KNO 3 ) in Malmö in 1767–1768,
1
Wilcke’s suspicion was of course unfounded.
2
Christopher Merret (c. 1615–1695). British physician and scientist.
21.1 Scheele’s Discovery of Oxygen
279